This invention relates to disposable chemical thermal packs, and more particularly to triggers for activating such packs.
Most hospitals require that blood samples be taken from new born infants during the first days after birth. Since one of the biggest body masses of a new born is his or her heel, blood for tests is generally drawn from the heel area. The problem with the heel as a source of blood is that a new born's blood circulation is poor. If blood circulation in the heel area is not increased before testing, drawing blood for testing may have an adverse affect on the infant and cause complications.
It is well known that heat causes blood flow to increase at the site where the heat is applied. Heat applied to the new born's heel area before blood is drawn for testing will increase blood flow into the heel area and prevent complications from the test.
Heat packs have long been used in various forms in the medical and sports fields. They are particularly useful for warming the heels of new born infants before blood is drawn for various tests. Current heat packs utilize supercoolable aqueous salt solutions wherein the temperatures as well as the duration of the heat given off can be controlled. Various salt solutions such as sodium acetate and calcium nitrate tetrahydrate are examples of such solutions.
Heat packs used as heel warmers today are of the reusable type. They feature a supercoolable aqueous solution together with a metallic activator device. Metallic activators have well documented problems associates with their use, but are still used to ensure reusability of the pack.